Simulation And Experimental Studies On Magnetically Coupled Piezoelectric Energy Harvester Based On Fluid Induced Vibration

In recent years,the piezoelectric energy harvesting technology for low-power microelectronic products has attracted the attention of many scholars.The flow-induced vibration piezoelectric energy harvesting technology,which combines the piezoelectric energy harvesting technology with the surrounding environment,has become the current research hotspot because it can more truly simulate the normal working condition of the energy harvesting device.In this paper,the magnetic field is coupled to the piezoelectric energy harvesting system working in the water flow field,and a magnetic coupling piezoelectric energy harvesting system based on flow-induced vibration is proposed to achieve high efficiency energy harvesting in the low-speed water flow environment.Firstly,the mathematical model of the magnetic coupling piezoelectric energy harvesting system is established,and the equivalent parameters of the model are obtained by theoretical derivation combined with experimental method.For the complex changes of the introduced magnetic field,the solution of magnetic force model in the system is determined.The output characteristics of the energy harvester are obtained by the preliminary numerical solution of the mathematical model,and compared with the experimental results,the correctness of the established model is verified.Then,based on the established mathematical model,the numerical simulation of single cylinder magnetic coupling piezoelectric energy harvesting system is carried out,and the influence of magnet polarization direction,initial spacing between magnets,cylinder diameter and mass ratio on the energy harvesting characteristics of the system is analyzed.Research shows: Under the effect of magnetic repulsion,the starting velocity of the system decreases obviously,the output of the low velocity section increases,and the smaller the magnet spacing is,the more obvious the improvement is.Under the effect of magnetic attraction,the peak voltage and effective bandwidth of the system are significantly improved,and the smaller the magnet spacing is,the more obvious the improvement is.Without changing other parameters of the energy harvester,increasing the diameter of the cylinder or decreasing the mass ratio of the cylinder,the energy harvesting characteristics of the system can be improved significantly.Then,the fluid simulation analysis of the piezoelectric energy harvesting system with tandem double cylinders under the action of magnetic repulsion is carried out,Under the conditions of different mass ratios and diameters of the cylindrical oscillators,the influence of the diameter of the upstream fixed cylinder and the center distance of the double cylinders on the energy harvesting characteristics of the system is studied.Research shows:Ensure that the other parameters of the system remain unchanged.Under the conditions of fixed column diameters of 5 mm and 10 mm,the smaller the center distance of the double cylinders,the better the output characteristics of the system.With the decrease of the diameter of the upstream fixed cylinder,the output voltage,the effective bandwidth and the energy harvesting performance in the whole velocity range of the system are significantly improved,and the output characteristics of the system are more sensitive to the change of the center distance.By increasing the diameter or mass ratio of the cylindrical vibrator,the overall output of the system is significantly improved.Compared with the magnetic single-cylinder system,the peak voltage increase rate of MPEH052 is89.8%,and the energy harvesting performance increase rate is 77.2%.Finally,the prototype of the system is developed to carry out underwater experiments,and the influence of system parameters on the energy harvesting characteristics is analyzed.Comparing the experimental results with the simulation results,the correctness of the mathematical model and simulation analysis is verified.